Thanks Gordon
I tended to view RTJ as an alternative to a welded joint more than an alternative to a conventional gasket and flange pair. Guess I'm getting old-fashoined.
Perhaps Davis doesnt need to become a car salesman after all.
Cheers
Steve
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=aTLJ1kEDKcVfmgfE2_i8spq9nWk64MQo1Qr3FipVroWr2jRdndvkjm2DDW8BkxCIwsH8VjEEFkSsAVUMF_9TFg">Gordon.Reddek@Alcan.com</a> [mailto:<a href="/group/PipingDesign/post?postID=aTLJ1kEDKcVfmgfE2_i8spq9nWk64MQo1Qr3FipVroWr2jRdndvkjm2DDW8BkxCIwsH8VjEEFkSsAVUMF_9TFg">Gordon.Reddek@Alcan.com</a>]
Sent: Monday, February 16, 2004 2:30 PM
To: <a href="/group/PipingDesign/post?postID=UVx_xhd4Mb_cvAAzsXZVr5_REQi4WAUpedOpQ8RE3UBMstpRySy0tmzAa7hghZm1ou2UfVqhI6E5j1wj38-OfHH3hRw">PipingDesign@yahoogroups.com</a>
Subject: RE: [PipingDesign] Current Interesting Link - SPO Compact
Flange
Steve,
There are heaps of disadvantages, most of them already mentioned by
yourself.
They are a hard surface joint so the surfaces must be well machined,
clean, uncorroded etc. Nothing is worse than RTJ flanges left open and
exposed to the weather. The moment they have corroded they are impossible
to seal without remachining... Also, the joints must line up properly. You
simply can not rely on the slack in the bolts to take up bad alignment.
The joints are big and bulky and the flanges have to be parted to get the
ring out because the ring sits in the groove in both flanges. So on the
surface of it looks like a bad joint. Well, if you run a clean
installation and do not allow the equipment to corrode, if you design the
pipework so that there is either enough flexibility to part joints, or
spools can be dropped out to easily remove rings, and if you fabricate the
pipework so that the pipes align well, they are as good a joint as any
other, in fact the joint of choice on most oil and gas high pressure
equipment. I can not remember seeing another type of joint on an oil or
gas well head assembly ever. Like all things engineering there is no
perfect solution. The RTJ joint has its place and that place is where
flexible type gaskets become problematic. In the oil and gas business
flexible gaskets are used on flat faced flanges at ANSI 150# rating and
raised face flanges up to ANSI 600# or 900# . RTJ's are just about always
used at ratings above that. The reason becomes obvious if you think of
it. Up to about ANSI 900# rating the frictional grip between the flange
faces and the gasket are obviously sufficient to prevent the gasket being
distorted or pushed out of the flange sideways. When you get to ANSI
1500# the experience is that a solid ring bound in a groove does the best
job. It is horses for courses I am afraid.
Just as an aside, the intent of my original email was not to defend the
RTJ as a gasket system but to help Suresh understand the use of a seal
ring. He obviously does not work in an industry that uses them.
"Steve McKenzie" <mechproj@xtra.co.nz>
16/02/2004 09:13 AM
Please respond to PipingDesign
To: <PipingDesign@yahoogroups.com>
cc:
Subject: RE: [PipingDesign] Current Interesting Link - SPO
Compact Flange
Hi Gordon
What are the disadvantages of the RTJ?
I had heard over the years:
Fussy to align (e.g. cold spring).
Difficult to repair sealing face damage.
Extreme cleanliness required during assembly.
Joint arrangement needs careful design to permit dismantling, e.g. removal
of valves.
Joints requiring frequent dismantling can be troublesome.
I have only used them on tubestill oil heaters for fire prevention
reasons.
They worked well, but I do remember a number of fitters grizzling about
the
general use of RTJs.
Perhaps you could offer a more informed opinion than mine, as mine is
based
only on hearsay and not personal experience.
Davis may have something useful to add - if he can get some time off from
the car sales lot.
Cheers
Steve
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=aTLJ1kEDKcVfmgfE2_i8spq9nWk64MQo1Qr3FipVroWr2jRdndvkjm2DDW8BkxCIwsH8VjEEFkSsAVUMF_9TFg">Gordon.Reddek@Alcan.com</a> [mailto:<a href="/group/PipingDesign/post?postID=aTLJ1kEDKcVfmgfE2_i8spq9nWk64MQo1Qr3FipVroWr2jRdndvkjm2DDW8BkxCIwsH8VjEEFkSsAVUMF_9TFg">Gordon.Reddek@Alcan.com</a>]
Sent: Monday, February 16, 2004 11:53 AM
To: <a href="/group/PipingDesign/post?postID=UVx_xhd4Mb_cvAAzsXZVr5_REQi4WAUpedOpQ8RE3UBMstpRySy0tmzAa7hghZm1ou2UfVqhI6E5j1wj38-OfHH3hRw">PipingDesign@yahoogroups.com</a>
Subject: Re: [PipingDesign] Current Interesting Link - SPO Compact
Flange
Suresh,
Most flanges have a fairly soft gasket between them to form the seal that
prevents the fluid escaping from the flanged joint. Common gaskets are
made from a sheet of fibrous material bound in a cement type compound, or
rubber. They can also be a layer of corrugated steel or a complicated
layer made up from a spiral of stainless steel and fibrous material. Just
about any idea you can think of to form a seal between the faces of the
flanges has already been developed and are in use. A seal ring is simply
a hard ring placed between the flanges to form a seal like a gasket. It
always sits in a groove machined into the face of each flange. The
grooves in the flanges and the seal rings have to be carefully machined to
match each other well. Here too there are a number of possible designs
but the most common is called a RING TIGHT JOINT which is commonly
abbreviated to RTJ.
The following is a site you can visit which shows details of RTJ flanges.
Click on the RTJ flange section.
<a href="http://www.texasflange.com/Dimensioncutsheet.htm">http://www.texasflange.com/Dimensioncutsheet.htm</a> You will notice that the
flanges all have grooves into which the seal ring fits.
This system has a number of advantages. The ring aligns the joint exactly
so the flange is always perfectly aligned when assembled. The seal ring
is wedged into the groove and contacts the groove along two lines of
contact in each groove. When you tighten up the flange all the force
goes into pressing the ring into the groove and the contact force along
those lines of contact are very high indeed, and that is what makes it an
effective sealing device. These rings seal so well that they are the most
commonly used sealing method in large high pressure installations.
Surf the web using the terms "RTJ" and "Flange" in the search engine. You
will find heaps if very interesting information on this type of joint.
<a href="/group/PipingDesign/post?postID=6c3MtAMMp-EOrKUKFeNUERXLpQSavVneJJnlLFDgygvrAzvHD8MBhOr_xIz_rcaxXkfOHvFgqZTn6NMAdRqDrWxRBgg">Jagarlamudi.Suresh@ril.com</a>
14/02/2004 12:57 PM
Please respond to PipingDesign
To: <a href="/group/PipingDesign/post?postID=UVx_xhd4Mb_cvAAzsXZVr5_REQi4WAUpedOpQ8RE3UBMstpRySy0tmzAa7hghZm1ou2UfVqhI6E5j1wj38-OfHH3hRw">PipingDesign@yahoogroups.com</a>
cc:
Subject: Re: [PipingDesign] Current Interesting Link - SPO
Compact Flange
Dear friends,
What is the meaing of sealring?
I know a little bit of information about flange design,But I did not hear
sealring?
please explain what it means?
from
suresh.J
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